Vehicle surface impact detection

Abstract

Systems and methods are provided for using sensors and signal processing to detect vehicle surface impacts. In particular, a sensor and signal processing approach is provided for detecting impacts, with the results having a low false positive rate. The approach reduces operator costs by reducing operator involvement through improved automated detection technology. Additionally, systems and methods are provided for distinguishing chassis-driven fascia vibration from impact-driven fascia vibration.

What is claimed is: 
     
       1. A system for detecting an impact on a vehicle, comprising:
 a first transducer configured to generate a first input signal; 
 a second transducer configured to generate a second input signal; 
 a coherence module configured to:
 receive the first input signal and the second input signal, 
 determine first spectra for the first input signal for each of a plurality of time windows, 
 determine second spectra for the second input signal for each of the plurality of time windows, and 
 determine a coherence measurement for each of the plurality of time windows based on respective first spectra and respective second spectra; and 
 
 a filter module configured to:
 detect a subset of the plurality of time windows for which a respective coherence measurement equals one, 
 identify a subset of first spectra corresponding to the subset of the plurality of time windows, 
 identify a subset of second spectra corresponding to the subset of the plurality of time windows, 
 filter out the subset of first spectra and the subset of second spectra, and generate a filtered transducer signal. 
 
 
     
     
       2. The system of  claim 1 , wherein the first spectra are first acceleration spectra of the first transducer and wherein the second spectra are second acceleration spectra of the second transducer. 
     
     
       3. The system of  claim 1 , wherein the filter module is a first filter module and further comprising a second filter module positioned between the first and second transducers and the coherence module, and configured to:
 receive the first input signal, 
 receive the second input signal, 
 filter selected frequencies from the first input signal and generate a filtered first input signal, 
 filter selected frequencies from the second input signal and generate a filtered second input signal, and 
 transmit the filtered first input signal and the filtered second input signal to the coherence module. 
 
     
     
       4. The system of  claim 3 , wherein the selected frequencies include at least one of: frequencies above about 800 Hz, frequencies above about 500 Hz, and frequencies around 2 kHz. 
     
     
       5. The system of  claim 1 , wherein the coherence module is further configured to:
 determine a cross spectrum for each of the plurality of time windows, and 
 calculate the coherence measurement based in part on the cross spectrum. 
 
     
     
       6. The system of  claim 5 , wherein the cross spectrum is based on the first input signal and the second input signal. 
     
     
       7. The system of  claim 5 , further comprising an impact detection module configured to detect an impact on the vehicle based on the filtered transducer signal. 
     
     
       8. The system of  claim 7 , wherein the coherence module is further configured to determine a phase of the cross spectrum, and wherein the impact detection module is further configured to determine a relative arrival time of the impact at each of the first and second transducers based on the phase of the cross spectrum. 
     
     
       9. The system of  claim 8 , wherein the first transducer is positioned on a vehicle chassis and the second transducer is positioned on an interior side of a vehicle surface. 
     
     
       10. The system of  claim 9 , wherein the impact detection module is further configured to determine, based on each of the relative arrival times, that the impact was caused by chassis driven motion. 
     
     
       11. The system of  claim 9 , wherein the impact detection module is further configured to determine, based on each of the relative arrival times, that the impact originated from a vehicle fascia. 
     
     
       12. The system of  claim 9 , wherein the coherence measurement is a first coherence measurement, and wherein the coherence module is further configured to compare the second input signal with data from an inertial measurement unit and generate a second coherence measurement, and wherein the impact detection module is further configured to determine, based on the second coherence measurement, one of:
 the impact originated from a vehicle power-train and suspension, or 
 the impact originated from a vehicle fascia. 
 
     
     
       13. A method for detecting an impact on a vehicle, comprising:
 receiving a first input signal from a first transducer positioned on the vehicle; 
 receiving a second input signal from a second transducer positioned on the vehicle; 
 determining first spectra for the first input signal for each of a plurality of time windows; 
 determining second spectra for the second input signal for each of the plurality of time windows; 
 determining a coherence measurement for each of the plurality of time windows based on respective first spectra and respective second spectra; 
 detecting a subset of the plurality of time windows for which the respective coherence measurement equals one; 
 identifying a subset of first spectra corresponding to the subset of the plurality of time windows; 
 identifying a subset of second spectra corresponding to the subset of the plurality of time windows; 
 filtering out the subset of first spectra and the subset of second spectra; 
 generating a filtered transducer signal; and 
 detecting an impact on the vehicle based on the filtered transducer signal. 
 
     
     
       14. The method of  claim 13 , further comprising:
 dividing the first input signal into multiple first bands; 
 dividing the second input signal into multiple second bands; and 
 performing a first transfer function on each of the multiple first bands to evaluate each of the first bands; and 
 performing a second transfer function on each of the multiple second bands to evaluate each of the second bands. 
 
     
     
       15. The method of  claim 13 , further comprising, dividing the first spectra, based on the coherence measurement, into a first portion of first spectra that represent chassis-driven signals and a second portion of first spectra that represent noise-driven signals. 
     
     
       16. The method of  claim 13 , further comprising:
 determining a cross spectrum for each of the plurality of time windows based on the first input signal and the second input signal; and 
 calculating the coherence measurement based in part on the cross spectrum. 
 
     
     
       17. The method of  claim 16 , further comprising:
 determining a phase of the cross spectrum; and 
 determining a relative arrival time of the impact at each of the first and second transducers based on the phase of the cross spectrum. 
 
     
     
       18. The method of  claim 17 , further comprising determining, based on the relative arrival time, one of:
 the impact was caused by chassis driven motion, or 
 the impact originated from a vehicle fascia. 
 
     
     
       19. A vehicle having an impact detection system, comprising:
 a plurality of transducers, including a first transducer configured to generate a first input signal and a second transducer configured to generate a second input signal; and 
 an onboard computing system, comprising:
 a coherence module configured to:
 receive the first input signal and the second input signal, 
 determine first spectra for the first input signal for each of a plurality of time windows, 
 determine second spectra for the second input signal for each of the plurality of time windows, and 
 determine a coherence measurement for each of the plurality of time windows based on respective first spectra and respective second spectra; 
 
 a filter module configured to:
 filter out a subset of first spectra and a subset of second spectra based on the coherence measurement, and 
 generate a filtered transducer signal; and 
 
 an impact detection module configured to detect an impact on the vehicle based on the filtered transducer signal. 
 
 
     
     
       20. The vehicle of  claim 19 , wherein the coherence module is further configured to:
 determine a cross spectrum for each of the plurality of time windows, and 
 calculate the coherence measurement based in part on the cross spectrum.